Concentric bore: Used primarily for clean, homogeneous flow of liquids, gases, or vapors that are relatively non-viscous. The bevel is matched at a 45 degress angle to the desired edge thickness where called for by ISA/AGA/API/ANSI specifications.

Eccentric bore: Used primarily for measurement of entrained solids or slurries. The eccentric bore can also be used to measure vapors & gases where condensation is present. The eccentric bore is offset to where the bore edge is inscribed in a circle that is 98% of the line I.D.

Segmental Bore The segmental bore is located in the same way that the eccentric bore is. These bores are used primarily for slurries or extremely dirty gases where the flow may contain impurities heavier than the fluid.

Quadrant Bore: This type of orifice bore is primarily used in the measurement of high viscocity flow such as heavy crude, syrups and slurries. The inlet is a quarter of a circle and the plate thickness must be as least as thick as the radius of the inlet. The quadrant bore is always recommended where the Reynolds Number factor is less than 10,000.